Conventional slate tile roofs are highly resistant to high winds due to the typical overlapping of three layers of slate along each row or course of slate. That is, the weight of two additional tiles bears down on a lower or bottom tile to press downwardly and hold the bottom tile in place during high winds. Moreover, conventional fasteners, such as nails, provide a strong wind resistant mounting of the slate tiles to the underlying roof.
Newer slate tile roofing systems eliminate the “three layer” conventional system noted above. These systems overlap a lower or bottom tile with a small portion of a single upper tile. While these systems are economical, as they use less tile per unit area of roof and reduce the weight of the tile bearing on an underlying roof, they do not perform well in high winds. That is, because less weight is applied to each row of tiles, it is easier for the wind to flow beneath a tile and lift it off the roof.
This wind problem has proven particularly acute when roofing tiles are secured with conventional “hook and strip” type fasteners. These fasteners provide an elongated strip having a series of hooks secured along the strip at regular spacings. Once a strip is properly nailed or otherwise fixed to a roof, an installer can quickly and easily insert roofing tiles into the open mouth of the hooks so as to hold the tiles in place on the roof. No nails are driven through the roofing tiles so that only wire hooks hold the tiles in place.
When wind flows under a tile held by one or more hooks on a hook and strip mounting, the resilient wire which forms the hooks bends upwardly so that the mouth on the hook opens up with the free end of the hook taking a permanently open set, thereby releasing a tile from the hook. The result is a lost tile, blown away by the wind.